Remove the priv field and let video_get/set_drvdata use dev_get_drvdata
and dev_set_drvdata instead.

Convert all drivers that still used priv directly.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>